The invention relates generally to imaging media loading in imaging systems. Specifically, the invention relates to a method and apparatus for increasing the likelihood of correct imaging media loading.
The ever-changing demands of global commerce, coupled with the almost unlimited capabilities of state-of-the-art imaging systems, has resulted in a need for a wide variety of document types and formats. The days of xe2x80x9cletter or legalxe2x80x9d have gone the way of carbon paper and mimeographs. Imaging systems are capable of handling a variety of standard sizes, such as letter, legal, A4, and A5-ISO, as well as custom sheet sizes.
Rather than require system users to have on hand a different sheet tray for each sheet size, it is known to provide cassette trays having the ability to handle a relatively wide range of sizes. Such trays are sometimes provided with sliding rear adjustable xe2x80x9cbackstopsxe2x80x9d which may accommodate different sheet lengths, and/or side slide-plates adjustable to communicate sheet size information to the printer central control system.
Two approaches to sheet size adjustability are exemplified by the optional 500-sheet tray and the standard 250-sheet tray associated with the Hewlett-Packard LaserJet 4000T printer. The optional 500-sheet tray supports standard sheet sizes, as well as custom sizes. The sheet size in the tray is communicated to the printer by contact with combinations of three levers on the side of the tray. The levers are capable of selective contact with switches on the interior of the sheet infeed housing when the tray is inserted into the printer. Each sheet size is associated with a unique set of lever positions. The levers are moved in and out by the slide-plate, which is mounted on the side of the tray. The slide-plate is provided with a plurality of holes corresponding to the lever combinations associated with the various sheet sizes. Levers are prevented from actuating their associated switches when the levers are aligned with holes, and can actuate switches when they are aligned with the xe2x80x9cflatsxe2x80x9d, or closed portions of the slide-plate. The slide-plate is moved-by turning a dial located on the side of the tray, which serves to push or pull the slide-plate. The printer user is required to manually set the dial for each paper size, which may be perceived as inconvenient.
The standard 250-sheet trays are equipped to automatically sense sheet size. The backstop of the tray is movable, and is mechanically linked to the slide-plate. When the backstop is moved to positions corresponding to standard sizes, the slide-plate is moved to a position exposing the proper levers, as with the optional 500-sheet tray. Although adjustment of the tray communicates differences between standard sizes automatically, the standard tray is unable to accommodate custom sizes.
Another typical adjustable tray is that associated with the Optra S2450 printer manufactured by Lexmark. The Optra S2450 operates in much the same way as the LaserJet 4000 standard tray, but also permits adjustment for some custom sizes. The Optra 2450 slide-plate has holes for standard sizes. When the backstop moves the slide-plate to a non-standard position, all levers are actuated, thus setting the switches to read a custom size. Unfortunately, the backstop and slide-plate of the Optra 2450 tray are incapable of independent adjustment. Consequently, the Optra S2450 tray cannot accommodate custom sheet sizes having the same length as standard sizes.
The patent literature also presents examples of adjustable imaging media trays, as shown in U.S. Pat. No. 5,901,952 to Hourtash. The Hourtash patent is directed to a paper supply tray having a bottom wall, left and right side walls, a front wall and a rear wall; a side wall paper guide laterally movable with respect to and connected to the supply tray. A front wall paper guide is longitudinally moveable with respect to and connected to the supply tray. The apparatus further includes a mechanical connector that engages both the paper guides in a manner such that the movement of one of the guides generates a corresponding movement of the other guide. The apparatus provides for a coupled width and length adjustment thereby allowing the user to conform both dimensions with only one manipulation
In another example, U.S. Pat. No. 5,574,551 to Kazakoff, automatic detection of the size of print media in a supply bin is provided by electrical devices. Adjustable print media alignment fences are operatively connected to the electrical devices, such as potentiometers, photovoltaic strips, photoemitter-photodetector arrays, or the like. The output signals from the electrical devices are correlated to width and length dimensions of the print media or the absence of print media availability. Embodiments are disclosed for standard and custom print media size detection.
The adjustability of these known systems present a different problem. Specifically, when backstops or side guides are adjusted at or near the midpoint of the tray, the xe2x80x9cunusedxe2x80x9d side of the tray may be of similar size to, or even larger than, the xe2x80x9cloadingxe2x80x9d side of the tray. Consequently, users loading media into the tray are susceptible to confusion as to which side of the tray the imaging media is to be placed. It has been proposed to place labels in the unused side of the tray to warn users against placing media incorrectly. Unfortunately, such labels are largely ignored and thus ineffective.
It can be seen from the foregoing that the need exists for a simple, inexpensive, arrangement for reducing the likelihood of incorrect imaging media placement in an adjustable media tray.
The present invention is directed to an imaging media tray including at least one adjustable guide operatively connected to an interior surface of the imaging media tray. The guide divides the interior of the tray into a loading section and an unused section. A blocking mechanism is secured in the unused section of the media tray to prevent a user of the tray from loading imaging media into the unused section of the tray. The blocking mechanism can be provided as an adjustable blocking element with a an expandable and contractible mechanical blocker connected between the at least one adjustable guide and an interior wall of the tray. Illustrated embodiments show the blocker as a telescoping member and as a pivoting cross member arrangement.